#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int map[403][403];
int main()
{
	int n, m, r, sum = 0;
	scanf("%d%d%d", &n, &m, &r);
	int x, y;
	for (int e = 0; e < m; e++) {
		scanf("%d%d", &x, &y);
		for(int i=0,j=0;i*i+j*j<=r*r;i++,j=0)
			for (; i * i + j * j <= r * r; j++) {
				map[x + i + 100][y + j + 100] = 1;
				map[x - i + 100][y + j + 100] = 1;
				map[x + i + 100][y - j + 100] = 1;
				map[x - i + 100][y - j + 100] = 1;
			}
	}
	for (int a = 101; a <= 200; a++)
		for (int b = 101; b <= 200; b++)
			sum += map[a][b];
	printf("%d", sum);
	return 0;
}